OSD3358 not booting from SD card on custom board design

[Manish]

Hi,

I am working on a OSD3358 custom board, the reference design is from Pocket beagle, I am not sure where the problem is. This is the first time I’m designing for the OSD3358 Chip.

I have tried both the methods mentioned in the forum posts #4733 and #4608 regarding the EEPROM ID check. Still I am unable to boot.The image I am using – AM3358 Debian 10.3 2020-04-06 4GB SD IoT and even nothing is showing up on UART 0. This led me to further review the design of my board.

I have a few doubts regarding my design , It would be of great help to review my design before proceeding further on the design changes. This is my github link : https://github.com/Manish-0521/osd3358.git

1. Maybe the Trace width of SD card lines in the PCB design is wrong, I have attempted on making it Single Co-Planar 50 OHM impedance.

2. I am turing the device on from the USB and the Trace width of VIN_USB is less in my design, as per the forums i have noticed that due to Inrush Current of 1.5A there might be an issue. I am getting the correct voltages on the Test points VDDS_DDR, VDD_CORE, VDD_MPU, VDDS_PLL. So I am assuming the Power is fine. But i did not check the sequence of turning on of these voltages.

Please review the schematics too.

Thanks in advance,
Manish

[Neeraj Dantu]

Manish,

Initial look into the schematics does not reveal anything obviously incorrect. Although 1 thing I noticed was both pull-ups and pull-downs for Address setting of IC1 seem to be populated, which might mess withe EEPROM configuration as EEPROM inside OSD3358-SM is on address 0x50. May not be an issue, but recommend checking and making sure the external EEPROM is on a different address.

If you are getting outputs on power rails, that would mean that the PMIC is up. Can you double check all voltage rails are OK according to https://octavosystems.com/app_notes/osd335x-sm-power-application-note/?

When there is no SD card, do you get “CCCC” output on UART0? If so, this is an indication that the processor has booted correctly and searching for a boot media.

The other things to check is 24MHz and 32KHz clock signals.

One way you can completely bypass EEPROM is by using EEPROM Blank image as described in https://github.com/RobertCNelson/omap-image-builder/tree/master/octavo. You can build this image on your machine by selecting octavo-blank-eeprom.conf while running https://github.com/RobertCNelson/omap-image-builder/tree/master/octavo#generate-image-file.

When booting with the SD card, you should be able to see activity on SD CLK and CMD lines, if you have an oscilloscope, this would be a debug step to understand whether the processor is attempting to boot from the SD card.

Please let us know if you have an update on the debug,

Best,

Neeraj

[Manish]

Hi Neeraj,

Thank you for your response. The I2C address of the EEPROM has been configured appropriately.

Here are the voltage readings I observed:

• VDDS_DDR: 1.5V
• VDD_CORE: 1.1V
• VDD_MPU: 1.1V
• VDDS_PLL: 1.8V

Other voltage rails also appear to be within acceptable ranges.

Regarding the 24 MHz oscillator, I noticed there is no clock signal present when observed on the oscilloscope. It shows a constant high signal instead of an oscillating waveform.

Additionally, when monitoring the SD_CLK and CMD lines, there is no activity on either line. Both remain at a constant high signal, even when the SD card is inserted.

I managed to check part of the power sequence using the oscilloscope (50 MHz, 2-channel). Specifically, I monitored:

• Channel 1: SYS_RTC_1P8V
• Channel 2: SYS_VDD_1P8V

I am attaching an image of the observed power sequence. Since I am relatively new to using the oscilloscope.

I would appreciate your feedback or guidance on what are the next steps to take regarding this issue.

Thank you,
Manish

Attachments:

1. 

   SDS00001.bmp
   

[Neeraj Dantu]

Manish,

The power rail measurements look OK. The sequence of RTC_1P8 vs VDD_1P8 also looks OK.

However, lack of 24MHz on OSC0 input is concerning. This is the main clock input for the SoC and it needs this clock input to function. The lack of activity on SD_CLK and CMD lines is consistent with the fact that the main clock input for the SoC is not functional.

Please review the values for C4, C6 and R33 in your schematic. Take a look at Section “Input Clock Requirements” in AM335x datasheet: https://www.ti.com/lit/ds/symlink/am3358.pdf to understand OSC0 Crystal Circuit Requirements. Can you see 32KHz signal?

Best,
Neeraj

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